Simplify the following equation.
$$ {(100)}^{1\over2}.{(0.001)}^{1\over3}-{(0.0016)}^{1\over4}.{3}^{0}+({5\over4})^{-1} $$

An alloy of copper and aluminum has 40% copper. Another alloy of Copper and Zinc has Copper and Zinc in the ratio 2: 7. These two alloys are mixed in ratio 5:3. Quantity of aluminum is what percent more/less than the quantity of copper in final alloy.

Find the value of given equations

$$\left({216\over1} \right) ^{-{2\over3}}÷\left({27\over1} \right) ^{-{4\over3}}=? $$

X and Y are centres of circles of radius 9 cm. and 2 cm respectively XY=17 cm. Z is the centre of a circle of radius r cm which touches the above circles externally. Given that - ∠xzy = 90^o the value of r is -

A is 4 years younger than B. B is 12 years younger than C. 4 years hence the ratio between C and A is 9:5, Find the age of B.

If 5^√x + 12^√x = 13^√x, then x is equal to: 

If $$ {x+{1\over x}}=2$$ then find out the value of $${2x^2+2}\over{3x^2+5x+3}$$

A can do a work in 24 days and B is 20% more efficient than A. If C can do the work in 10 days more than B, then find the days taken by A and C together to complete the work.